Flow Battery Capacity Recovery System and Method

Abstract

This application discloses a flow battery capacity recovery system and method, belonging to the field of flow battery technology. The system connects the positive and negative electrode storage tanks to an ultraviolet photocatalytic microreactor via an inlet pipeline assembly and a gas return pipeline assembly. This allows the oxidizing gas generated by the positive electrode electrolyte to mix with the reducing gas generated by the negative electrode electrolyte. Within the microreactor, ultraviolet light irradiation triggers a combustion reaction, and the generated acidic gas is ultimately returned to the positive electrode electrolyte for absorption. Therefore, this system eliminates the need for external chemical recovery agents or heterogeneous catalysts. By converting the inherent side reaction gases during battery operation into acidic components that can be recovered by the positive electrode, it autonomously corrects the ion imbalance of the positive and negative electrode electrolytes, maintaining the valence balance of the positive and negative electrolytes. This suppresses and restores the battery capacity decay caused by continuous side reactions, extending the lifespan of the flow battery.

Description

Technical Field

[0001] This application relates to the field of flow battery technology, and in particular to a flow battery capacity recovery system and method. Background Technology

[0002] A flow battery is an electrochemical device suitable for large-scale energy storage. It stores and releases electrical energy through changes in the valence states of active substances in the positive and negative electrode electrolytes. However, during long-term cycling, side reactions such as hydrogen evolution continuously occur at the negative electrode, leading to an imbalance in the average valence states of active ions in the positive and negative electrode electrolytes, which in turn causes a continuous decline in battery capacity.

[0003] To restore battery capacity, it is usually necessary to introduce solid catalysts or chemical restorers into the electrolyte. For example, this can be achieved by loading solid catalysts into a catalytic reaction device to adsorb and convert active gases, or by directly adding reducing substances to the electrolyte. These methods all introduce additional chemicals into the battery system, and their residues or detached substances may contaminate the electrolyte, affecting the battery's long-term stability and lifespan. Summary of the Invention

[0004] This application provides a flow battery capacity recovery system and method that effectively restores the capacity of a flow battery without introducing foreign chemical substances, thereby at least partially solving the above-mentioned technical problems.

[0005] To achieve the above objectives, according to a first aspect of this application, a flow battery capacity recovery system is provided, comprising:

[0006] A positive electrode storage tank contains a positive electrode electrolyte, which is capable of generating oxidizing gas.

[0007] A negative electrode storage tank contains a negative electrode electrolyte, which is capable of generating reducing gas.

[0008] An air inlet pipeline assembly and an ultraviolet photocatalytic microreactor are provided. The air inlet of the ultraviolet photocatalytic microreactor is connected to the positive electrode storage tank and the negative electrode storage tank through the air inlet pipeline assembly. The ultraviolet photocatalytic microreactor is used to receive the mixture of the oxidizing gas and the reducing gas, and to initiate the combustion and explosion reaction of the mixture under ultraviolet light irradiation to generate acidic gas.

[0009] A gas reflux pipeline assembly connects the gas outlet of the ultraviolet photocatalytic microreactor to the positive electrode storage tank, and is used to transport the acidic gas to the positive electrode storage tank so that the acidic gas can be absorbed by the positive electrode electrolyte.

[0010] In some embodiments, the intake manifold assembly includes:

[0011] The first pipeline is connected to the gas outlet of the positive electrode storage tank;

[0012] The second pipeline is connected to the gas outlet of the negative electrode storage tank;

[0013] A three-way mixer has one inlet connected to the first pipeline and the other inlet connected to the second pipeline, and the outlet of the three-way mixer is used to output the mixed gas.

[0014] The third pipeline connects the outlet of the three-way mixer to the inlet of the ultraviolet photocatalytic microreactor.

[0015] In some embodiments, the intake piping assembly further includes a first one-way valve disposed on the third piping and configured to allow the mixed gas to flow from the three-way mixer to the ultraviolet photocatalytic microreactor.

[0016] In some embodiments, the diameter of the first pipeline is 1 to 3 times the diameter of the second pipeline.

[0017] In some embodiments, the gas reflux pipeline assembly includes a fourth pipeline, one end of which is connected to the gas outlet of the ultraviolet photocatalytic microreactor, and the other end is connected to the gas inlet of the positive electrode storage tank.

[0018] In some embodiments, the flow battery capacity recovery system further includes a negative pressure generating device for driving the flow of the oxidizing gas, the reducing gas, and the acidic gas.

[0019] In some embodiments, the negative pressure generating device includes an air pump disposed on the fourth pipeline.

[0020] In some embodiments, the gas reflux pipeline assembly further includes a multi-way switching valve and a fifth pipeline; one end of the fourth pipeline is connected to the first gas outlet of the multi-way switching valve to be connected to the gas outlet of the ultraviolet photocatalytic microreactor through the multi-way switching valve; one end of the fifth pipeline is connected to the second gas outlet of the multi-way switching valve, and the other end is connected to the gas inlet of the positive electrode storage tank.

[0021] The negative pressure generating device includes an air pump, which is installed on the fifth pipeline.

[0022] In some embodiments, the flow battery capacity recovery system further includes a positive electrode return line for conveying positive electrode electrolyte, and the gas return line assembly includes a sixth line;

[0023] The negative pressure generating device includes a Venturi bubble generator, which is located on the positive electrode return line and connected to the third outlet port of the multi-way switching valve through the sixth line.

[0024] In some embodiments, a three-way switching valve is provided on the positive electrode return line to switch the positive electrode return line to flow through the Venturi bubble generator or bypass the Venturi bubble generator.

[0025] In some embodiments, the fourth pipeline is provided with a second one-way valve, which is configured to allow the acidic gas to flow to the positive electrode storage tank; and / or,

[0026] The fifth pipeline is equipped with a third one-way valve, which is configured to allow the acidic gas to flow to the positive electrode storage tank; and / or,

[0027] The sixth pipeline is equipped with a fourth one-way valve, which is configured to allow the acidic gas to flow to the Venturi bubble generator.

[0028] In some embodiments, the ultraviolet photocatalytic microreactor includes:

[0029] The reactor shell surrounds a reaction chamber, which is connected to the gas inlet and gas outlet of the ultraviolet photocatalytic microreactor.

[0030] An ultraviolet light source is disposed inside the reaction chamber;

[0031] A light-transmitting cover is disposed inside the reaction chamber and fitted around the outer periphery of the ultraviolet light source.

[0032] In some embodiments, the reactor shell has a wall thickness of 5 mm to 10 mm and a radius of 15 mm to 60 mm; and / or,

[0033] The wall thickness of the light-transmitting cover is 5mm to 10mm, and the radius is 10mm to 30mm.

[0034] In some embodiments, the wavelength of the ultraviolet light source is 200nm to 400nm, and the power is 5W to 40W.

[0035] In some embodiments, the reactor shell includes a metal outer shell layer and a polymer inner liner layer, the polymer inner liner layer being disposed on the inner surface of the metal outer shell layer; and / or,

[0036] The light-transmitting cover is made of glass.

[0037] In some embodiments, the flow battery capacity recovery system includes a plurality of ultraviolet photocatalytic microreactors arranged in parallel with each other, the inlet end of each ultraviolet photocatalytic microreactor being connected to the inlet pipeline assembly, and the outlet end of each ultraviolet photocatalytic microreactor being connected to the gas return pipeline assembly.

[0038] According to a second aspect of this application, a method for restoring the capacity of a flow battery is provided, comprising:

[0039] The oxidizing gas generated by the positive electrode electrolyte in the positive electrode storage tank and the reducing gas generated by the negative electrode electrolyte in the negative electrode storage tank are mixed to form a mixed gas.

[0040] The mixed gas is passed into an ultraviolet photocatalytic microreactor, and a combustion and explosion reaction is initiated under ultraviolet light irradiation to generate acidic gas;

[0041] The acidic gas is passed into the positive electrode electrolyte for absorption.

[0042] In some embodiments, the flow of the oxidizing gas, the reducing gas, and the acidic gas is driven by negative pressure.

[0043] In some embodiments, the negative pressure is generated by an air pump.

[0044] In some embodiments, the negative pressure is generated by allowing the positive electrolyte to flow through a Venturi bubble generator.

[0045] In some embodiments, when the flow rate of the positive electrolyte is lower than a preset value, the flow path of the positive electrolyte is switched to bypass the Venturi bubble generator; and the air pump is started to generate the negative pressure.

[0046] In some embodiments, the flow battery capacity recovery method further includes:

[0047] Utilizing the instantaneous negative pressure generated after the combustion-explosion reaction is completed, new mixed gas is automatically drawn into the ultraviolet photocatalytic microreactor to repeat the combustion-explosion reaction until the concentration of the reducing gas is lower than the concentration limit of the combustion-explosion reaction.

[0048] In some embodiments, the oxidizing gas is chlorine or bromine, and the reducing gas is hydrogen.

[0049] In some embodiments, the wavelength of the ultraviolet light in the ultraviolet photocatalytic microreactor is 200 nm to 400 nm.

[0050] In some embodiments, the power of the ultraviolet light in the ultraviolet photocatalytic microreactor is 5W to 40W.

[0051] In some embodiments, after the step of passing acidic gas into the positive electrode electrolyte for absorption, the state of charge of the positive electrode electrolyte is 50% to 100%.

[0052] In the flow battery capacity recovery system of this application embodiment, the positive electrode storage tank and the negative electrode storage tank are connected to an ultraviolet photocatalytic microreactor via an inlet pipeline assembly and a gas return pipeline assembly. This allows the oxidizing gas generated by the positive electrode electrolyte and the reducing gas generated by the negative electrode electrolyte to mix. Within the microreactor, ultraviolet light irradiation triggers a combustion reaction, and the generated acidic gas is ultimately returned to the positive electrode electrolyte for absorption. Therefore, this system eliminates the need for external chemical recovery agents or heterogeneous catalysts. By converting the inherent side reaction gases during battery operation into acidic components that can be recovered by the positive electrode, it autonomously corrects the ion imbalance of the positive and negative electrode electrolytes, maintaining the valence balance of the positive and negative electrode electrolytes. This suppresses and restores battery capacity decay caused by continuous side reactions, extending the lifespan of the flow battery.

[0053] In the flow battery capacity recovery method of this application embodiment, the oxidizing gas and reducing gas generated by the positive and negative electrode electrolytes are mixed and introduced into an ultraviolet photocatalytic microreactor to initiate a combustion reaction under light irradiation. The resulting acidic gas is then passed into the positive electrode electrolyte for absorption. This method achieves capacity recovery based on a physicophotochemical process, directly utilizing the gaseous byproducts generated within the battery system. Through in-situ conversion and reuse, it effectively restores the balance of active materials in the electrolyte. The entire process requires no external addition, reducing potential electrolyte contamination and secondary degradation.

[0054] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0057] Figure 1 This is a schematic diagram of the structure of the flow battery provided in the embodiments of this application;

[0058] Figure 2 This is a schematic diagram of the flow battery capacity recovery system provided in Embodiment 1 of this application;

[0059] Figure 3 This is a schematic diagram of the flow battery capacity recovery system provided in Embodiment 2 of this application;

[0060] Figure 4 This is a schematic diagram of the flow battery capacity recovery system provided in Embodiment 3 of this application;

[0061] Figure 5 This is a schematic diagram of the flow battery capacity recovery system provided in Embodiment 4 of this application;

[0062] Figure 6 This is a schematic diagram of the structure of the ultraviolet photocatalytic microreactor provided in the embodiments of this application;

[0063] Figure 7 yes Figure 6 Schematic diagram of the AA section;

[0064] Figure 8 This is a flowchart of a flow battery capacity recovery method provided in an embodiment of this application.

[0065] Explanation of reference numerals in the attached figures:

[0066] 100-Positive electrode storage tank; 101-Positive electrode outlet; 102-First positive electrode inlet; 103-Second positive electrode inlet; 104-First positive electrode return tank; 105-Second positive electrode return tank; 200-Negative electrode storage tank; 201-Negative electrode outlet; 300-Inlet pipeline assembly; 310-First pipeline; 320-Second pipeline; 330-Three-way mixer; 340-Third pipeline; 350-First one-way valve; 400-UV photocatalytic microreactor; 410-Reactor inlet; 420-Reactor outlet; 430-Reactor shell; 431-Metal outer shell layer; 432-Polymer inner liner layer; 440-UV light source; 450 - Light-transmitting cover; 460-First flange; 470-Second flange; 480-Reaction chamber; 500-Gas reflux pipeline assembly; 510-Fourth pipeline; 520-Multi-port switching valve; 521-First gas outlet; 522-Second gas outlet; 523-Third gas outlet; 524-Gas inlet; 530-Fifth pipeline; 540-Sixth pipeline; 550-Seventh pipeline; 560-Second one-way valve; 580-Third one-way valve; 570-Fourth one-way valve; 610-Air pump; 620-Venturi bubble generator; 700-Positive electrode return pipeline; 710-Three-way switching valve; 720-First branch; 730-Second branch. Detailed Implementation

[0067] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0068] Please refer to Figure 1 As shown, a flow battery is a large-scale energy storage device based on electrochemical principles. This battery mainly consists of a stack, electrolyte, storage tanks, a fluid delivery unit, and a control and management module. Its core feature is that the positive and negative electrolytes are separately packaged and flow separately under the drive of a circulation pump, achieving the interconversion and storage of electrical energy and chemical energy through the transformation of the valence states of the active materials. Specifically, the system stores the positive and negative electrolytes in two separate tanks, and a delivery pump drives them to undergo a redox reaction as they flow through the stack. Inside the stack, the positive and negative electrolytes are separated by an ion exchange membrane (or separator) to prevent mixing. The battery can be charged by an external power source or discharged by connecting to a load.

[0069] Although flow batteries offer advantages such as high capacity scalability, wide operating temperature range, and long cycle life, a certain degree of capacity decay is still inevitable during repeated charge-discharge cycles. Taking vanadium redox flow batteries as an example, a significant reason for capacity degradation is the hydrogen evolution reaction at the negative electrode, which causes an increase in the average valence state of vanadium ions in both the positive and negative electrode electrolytes. (Positive electrode) VO 2 + / VO 2+ ,negative electrode V 3+ / V 2+ Initially, the masses of the positive and negative electrode active materials are equal. During the cycle, the negative electrode electrolyte continuously undergoes a hydrogen evolution reaction.

[0070] 2 V 2+ +2 H + =2 V 3+ +H 2↑

[0071] This process causes the concentration of pentavalent vanadium in the positive electrode electrolyte to gradually increase, and the average valence state of vanadium ions to continue to rise, directly leading to a gradual decrease in battery capacity.

[0072] To restore battery capacity, one common approach is to introduce a reducing agent into the positive electrode electrolyte at a high SOC (State of Charge). At this point, highly oxidizing, high-valence active ions react with the reducing agent and are reduced to lower-valence ions, effectively lowering the average valence state of active ions in both the positive and negative electrode electrolytes. However, this method continuously introduces reduction reaction residues, potentially affecting electrolyte purity and battery performance. Another, more commonly used approach is based on fuel cell principles: constructing a battery system using a reducing gas and the positive electrode electrolyte, and employing a noble metal catalyst to catalytically reduce the positive electrode active material, thereby lowering its valence state. However, this method has the drawback of easily detaching the noble metal catalyst and allowing it to enter the electrolyte, potentially exacerbating the hydrogen evolution reaction at the negative electrode and causing a rapid decline in battery capacity. In addition, an external catalytic reaction device can be installed to receive and fix the oxidizing gas released from the positive electrode storage tank 100, and introduce the elemental gas (usually hydrogen) lost from the negative electrode due to side reactions. This gas reacts with the oxidized catalyst to generate acidic gas, which returns to the negative electrode storage tank 200 and is absorbed by the negative electrode electrolyte. However, this method requires an external gas source, the control process is relatively complex, the cost is high, and there are certain safety hazards.

[0073] In view of this, embodiments of this application provide a flow battery capacity recovery system. This system can collect gaseous products generated by side reactions during the operation of the flow battery and convert them back into effective components that can be absorbed by the electrolyte. While achieving effective capacity regeneration, it can also avoid introducing foreign substances to contaminate the electrolyte and control energy consumption and system complexity as much as possible to maintain the high efficiency and stable operation of the battery system.

[0074] Please refer to the above as well. Figures 2 to 5 As shown, the basic components of the flow battery capacity recovery system provided in this application embodiment include a positive electrode storage tank 100, a negative electrode storage tank 200, an air inlet pipeline assembly 300, an ultraviolet photocatalytic microreactor 400, and a gas return pipeline assembly 500.

[0075] The positive electrode reservoir 100 is used to contain the positive electrode electrolyte of the flow battery. This positive electrode electrolyte typically contains one or more active ions and reducing ions. When the flow battery is in a high state of charge (SOC), the reducing ions in the positive electrode electrolyte can undergo a redox reaction with the high-valence active ions. As a result of this reaction, the high-valence active ions are reduced to a lower valence state, releasing oxidizing gases. Common oxidizing gases include chlorine or bromine vapor.

[0076] The negative electrode reservoir 200 is used to contain the negative electrode electrolyte of the flow battery. During long-term charge-discharge cycles in flow batteries, especially vanadium redox flow batteries, side reactions such as hydrogen evolution are prone to occur on the negative electrode side. These side reactions lead to the generation and accumulation of reducing gases, the most common of which is hydrogen. It is these side reaction gases that cause an imbalance in the total amount of active material in the positive and negative electrode electrolytes, thereby leading to a decrease in battery capacity.

[0077] The inlet piping assembly 300 constitutes the gas transport channel. The inlet end of this assembly is connected to the outlet ends of both the positive electrode storage tank 100 and the negative electrode storage tank 200, while its outlet end is connected to the inlet end of the ultraviolet photocatalytic microreactor 400. The main function of the inlet piping assembly 300 is to transport the oxidizing gas generated by the positive electrode electrolyte in the positive electrode storage tank 100 and the reducing gas generated by the negative electrode electrolyte in the negative electrode storage tank 200 to the ultraviolet photocatalytic microreactor 400. During the transport process, the two gases can be pre-mixed to form a mixed gas.

[0078] The ultraviolet photocatalytic microreactor 400 is one of the core devices of this system. It contains a sealed reaction chamber 480 and is equipped with an ultraviolet light source 440. When the mixed gas from the inlet pipeline assembly 300 enters this reaction chamber 480, under ultraviolet light irradiation of a specific wavelength (e.g., 200 nm to 400 nm), a rapid and violent gas-phase chemical reaction, i.e., a combustion-detonation reaction, occurs between the oxidizing gas and the reducing gas. This reaction converts the mixed gas into one or more acidic gases. For example, when the oxidizing gas is chlorine and the reducing gas is hydrogen, under ultraviolet light initiation, they combine to produce hydrogen chloride gas.

[0079] The gas reflux pipeline assembly 500 connects the gas outlet of the ultraviolet photocatalytic microreactor 400 to the positive electrode storage tank 100. Its function is to transport the acidic gas generated by the combustion reaction back to the positive electrode storage tank 100, allowing the acidic gas to be absorbed by the positive electrode electrolyte. Taking hydrogen chloride as an example, it dissolves in water to form hydrochloric acid, which can provide hydrogen ions that are utilized by the system, thereby helping to restore the chemical balance of the positive electrode electrolyte.

[0080] The system operates by creating a closed gas processing loop. Byproduct gases naturally generated during battery operation that cause capacity decay (such as hydrogen at the negative electrode) are collected and introduced into the UV photocatalytic microreactor 400 along with oxidizing gases generated at the positive electrode. Through a photochemical combustion reaction, these gases are converted into beneficial, absorbable acidic components for the positive electrode. This process requires no external solid catalysts or chemical restorers, avoiding potential electrolyte contamination. By effectively utilizing the battery's own byproducts through in-situ conversion and reuse, the system autonomously corrects the ion imbalance in the positive and negative electrode electrolytes, thereby suppressing and restoring battery capacity decay and achieving long-life, stable operation of the flow battery.

[0081] Please refer to Figure 2 In some embodiments, the air intake piping assembly 300 of the flow battery capacity recovery system includes multiple piping and a gas mixing unit.

[0082] Specifically, one end of the first pipe 310 is connected to the positive electrode outlet 101 of the positive electrode storage tank 100, and is used specifically to transport the oxidizing gas generated by the positive electrode electrolyte. One end of the second pipe 320 is connected to the negative electrode outlet 201 of the negative electrode storage tank 200, and is used specifically to transport the reducing gas generated by the side reaction of the negative electrode electrolyte. A three-way mixer 330 is disposed between the first pipe 310 and the second pipe 320. The three-way mixer 330 has two inlets and one outlet. One inlet is connected to the other end of the first pipe 310 to receive the oxidizing gas; the other inlet is connected to the other end of the second pipe 320 to receive the reducing gas. The two gases are thoroughly mixed as they flow through the three-way mixer 330 to form a homogeneous mixed gas, which is then output from its outlet. The third pipe 340 serves as a connecting channel, with one end connected to the outlet of the three-way mixer 330 and the other end connected to the reactor inlet 410 of the ultraviolet photocatalytic microreactor 400. This ensures that the mixed gas is stably delivered into the reaction chamber 480.

[0083] By employing the intake pipeline assembly 300, the system can systematically complete the entire process from gas collection, transportation to mixing. Its simple structure provides a stable and reliable gas source for subsequent photochemical combustion and explosion reactions.

[0084] In some embodiments, a first one-way valve 350 may be added to the third pipeline 340 to optimize gas flow control and improve system reliability. This first one-way valve 350 is configured to allow gas to flow in a single direction; specifically, it allows the mixed gas from the three-way mixer 330 to flow to the ultraviolet photocatalytic microreactor 400. This effectively prevents gas backflow and avoids the mixed gas flowing back into the three-way mixer 330 and even into the positive electrode storage tank 100 and the negative electrode storage tank 200.

[0085] By setting the first one-way valve 350, a predetermined airflow path can be maintained within the system. This not only helps ensure the stable operation of the reaction process within the UV photocatalytic microreactor 400, but also avoids concentration fluctuations or potential safety issues that may be caused by gas backflow, thereby improving the controllability and safety of the entire capacity recovery system.

[0086] Optionally, one-way valves may be added to the first pipeline 310 and the second pipeline 320 respectively. The one-way valve on the first pipeline 310 is configured to allow only the oxidizing gas to flow from the positive electrode reservoir 100 to the three-way mixer 330. Similarly, the other one-way valve on the second pipeline 320 is configured to allow only the reducing gas to flow from the negative electrode reservoir 200 to the three-way mixer 330.

[0087] This arrangement effectively prevents backflow of the mixed gas at the three-way mixer 330. Specifically, it avoids the reverse flow of oxidizing gas into the negative electrode reservoir 200 or reducing gas into the positive electrode reservoir 100, thus eliminating the adverse effects on the performance of the positive and negative electrolytes due to gas cross-contamination. Furthermore, it enhances the electrical and chemical isolation between the positive and negative electrode circuits to a certain extent, reducing the risk of internal short circuits or other side reactions caused by gas crosstalk. In addition, it works in conjunction with the one-way valve on the third pipeline 340, allowing the gas to flow more stably and orderly along a predetermined path within the system, improving the stability and reliability of the entire recovery process.

[0088] In some embodiments, in order to optimize the composition ratio of the mixed gas entering the ultraviolet photocatalytic microreactor 400, the physical structure of the first pipeline 310 and the second pipeline 320 can be configured.

[0089] Specifically, the inner diameters of the first pipe 310 and the second pipe 320 are set to different dimensions. The inner diameter of the first pipe 310 is configured to be 1 to 3 times the inner diameter of the second pipe 320. That is, the ratio of the diameters of the first pipe 310 and the second pipe 320 is (1~3):1, specifically, it can be any ratio among 1:1, 2:1, and 3:1, or any range between any two ratios. This allows for the passive regulation and balancing of the flow rates of oxidizing and reducing gases without relying on additional active control elements (such as flow valves), taking advantage of the characteristic that the resistance of fluid flow in the pipe is related to the pipe diameter.

[0090] Since the oxidizing gas generated by the positive electrode storage tank 100 and the reducing gas generated by the negative electrode storage tank 200 typically differ in their generation rates, adjusting the pipe diameter ratio of the delivery pipeline allows the two gases to enter the three-way mixer 330 at a volume ratio closer to the stoichiometric ratio. This facilitates a more complete and efficient combustion reaction in the subsequent ultraviolet photocatalytic microreactor 400, reducing waste or incomplete reactions caused by excess of a single reactant gas, thereby improving the overall processing efficiency and economy of the capacity recovery system.

[0091] Optionally, flow control valves, such as proportional valves or manual regulating valves, can be added to the first pipeline 310 and the second pipeline 320 respectively. By adjusting these valves, the instantaneous flow rates of the oxidizing gas and the reducing gas can be actively and precisely controlled. This allows the system to flexibly adapt to changes in the evolution rates of the positive and negative electrode gases under different operating conditions (such as different battery degradation levels and different SOC states), dynamically adjusting the ratio of the mixed gases to the optimal ratio, thereby ensuring that the combustion and explosion reaction within the ultraviolet photocatalytic microreactor 400 always proceeds under the most efficient conditions.

[0092] Please refer to this again. Figure 2 In some embodiments, the gas reflux pipeline assembly 500 includes a fourth pipeline 510. One end of the fourth pipeline 510 is connected to the reactor outlet 420 of the ultraviolet photocatalytic microreactor 400, and the other end is connected to an inlet of the positive electrode storage tank 100 (i.e., Figure 2 (Second positive electrode inlet 103). This fourth pipeline 510 constitutes the core channel for the return of acidic gas to the positive electrode storage tank 100. It can efficiently transport the acidic gas generated by the combustion reaction inside the ultraviolet photocatalytic microreactor 400 back to the cavity of the positive electrode storage tank 100. By setting the fourth pipeline 510, the system can timely and directionally transport the generated acidic products to the target location and effectively absorb them by the positive electrode electrolyte.

[0093] In some embodiments, the flow battery capacity recovery system further includes a negative pressure generating device that provides driving force for gas flow. Specifically, it drives three key gas paths: drawing oxidizing gas from the positive electrode reservoir 100, drawing reducing gas from the negative electrode reservoir 200, and pushing the acidic gas generated in the reaction back from the ultraviolet photocatalytic microreactor 400 to the positive electrode reservoir 100.

[0094] By introducing this negative pressure generating device, a negative pressure (i.e., a pressure lower than atmospheric pressure) can be actively generated in the pipeline downstream of the ultraviolet photocatalytic microreactor 400. This negative pressure is transmitted upstream through the gas return pipeline assembly 500, acting sequentially on the reaction chamber 480 of the ultraviolet photocatalytic microreactor 400, the inlet pipeline assembly 300, and finally reaching the top gas phase space of the positive electrode storage tank 100 and the negative electrode storage tank 200. Driven by this pressure difference, oxidizing gas and reducing gas are extracted from their respective storage tanks, enter the inlet pipeline assembly 300, and mix at the three-way mixer 330. They then flow into and fill the reaction chamber 480 of the ultraviolet photocatalytic microreactor 400, preparing the necessary reactants for the initial combustion and explosion reaction.

[0095] Therefore, in this embodiment, a major function of the negative pressure generating device is to provide the initial power for system startup, overcome the inertia of the system when it is stationary, establish the initial gas flow and reactant filling, so that the capacity recovery procedure can be started and carried out smoothly.

[0096] The specific implementation of this negative pressure generating device can be varied, such as using an air pump 610 for active suction, or using the Venturi effect to generate negative pressure. Its core purpose is to provide a controllable driving force for the gas circuit of the system.

[0097] Figure 2 The illustrated embodiment provides a specific implementation of a negative pressure generating device. This negative pressure generating device uses an air pump 610 as a power source. The air pump 610 is directly connected in series on the fourth pipe 510 of the gas return pipeline assembly 500. Its location is between the reactor outlet 420 of the ultraviolet photocatalytic microreactor 400 and the inlet of the positive electrode storage tank 100.

[0098] When the air pump 610 starts working, it generates a suction force (negative pressure) on its own air intake side, that is, the end facing the ultraviolet photocatalytic microreactor 400. This negative pressure is transmitted through the pipeline and acts on the reaction chamber 480 of the entire ultraviolet photocatalytic microreactor 400 and the upstream air intake pipeline assembly 300, thereby forming the driving force for gas flow.

[0099] The suction force can simultaneously extract the oxidizing gas from the positive electrode storage tank 100 and the reducing gas from the negative electrode storage tank 200, and mix them before flowing into the ultraviolet photocatalytic microreactor 400. At the same time, a pushing force is generated on the outlet side of the gas pump 610 (i.e., the end facing the positive electrode storage tank 100), effectively transporting the acidic gas generated by the reaction back to the positive electrode storage tank 100.

[0100] This configuration, which directly connects the air pump 610 in series with the return pipeline, enables the driving of all gas flow within the system. It features a compact structure, simple control logic, and effectively ensures continuous operation during the recovery process.

[0101] Please refer to Figure 3In some embodiments, the gas reflux pipeline assembly 500 includes a multi-way switching valve 520, a fourth pipeline 510, and a fifth pipeline 530. The multi-way switching valve 520 has an inlet port 524 and multiple outlet ports, with the inlet port 524 connected to the reactor outlet 420 of the UV photocatalytic microreactor 400. One end of the fourth pipeline 510 is connected to a specific outlet port of the multi-way switching valve 520, namely the first outlet port 521, and the other end is connected to the second positive electrode inlet port 103 of the positive electrode storage tank 100. One end of the fifth pipeline 530 is connected to another outlet port of the multi-way switching valve 520, namely the second outlet port 522, and the other end is connected to the first positive electrode inlet port 102 of the positive electrode storage tank 100. The first positive electrode inlet port 102 and the second positive electrode inlet port 103 can be the same port or different ports. A gas pump 610 of the negative pressure generating device is installed on this fifth pipeline 530.

[0102] In this embodiment, when the system requires the gas pump 610 to operate, the multi-way switching valve 520 is operated to connect its inlet port 524 to the second outlet port 522 connected to the fifth pipeline 530. The gas pump 610 is then started, drawing gas from the reactor outlet 420 of the ultraviolet photocatalytic microreactor 400 through the fifth pipeline 530 and the multi-way switching valve 520. This operation creates a negative pressure in the ultraviolet photocatalytic microreactor 400 and its upstream pipeline, driving the oxidizing and reducing gases to flow in and undergo a combustion reaction. Simultaneously, the generated acidic gas is pushed back to the positive electrode storage tank 100 via the multi-way switching valve 520 and the fifth pipeline 530.

[0103] When the mixed gas inside the ultraviolet photocatalytic microreactor 400 is ignited by ultraviolet light, a combustion-explosion reaction occurs, generating extremely high pressure instantaneously. This pressure acts as a driving force, propelling the acidic gas generated in the reaction chamber 480 at high speed. At the moment the acidic gas is violently expelled, the pressure inside the reaction chamber 480 drops sharply, creating a momentary negative pressure zone. This negative pressure, generated by the reaction itself, is immediately transmitted upstream through the inlet pipe assembly 300, thereby generating a suction effect that automatically draws a new batch of oxidizing and reducing gases from their respective storage tanks and into the reaction chamber 480.

[0104] At this point, the multi-way switching valve 520 can be operated to keep its air inlet 524 connected to the first air outlet 521 connected to the fourth pipeline 510, while simultaneously closing the second air outlet 522 connected to the air pump 610. The system thus switches to self-driving mode.

[0105] Subsequently, as long as the ultraviolet light source 440 remains on and the gas concentrations provided by the positive electrode storage tank 100 and the negative electrode storage tank 200 are within the combustion and explosion limits, the aforementioned processes of gas mixture intake, photo-induced combustion and explosion, high-pressure exhaust, and instantaneous negative pressure intake will automatically repeat, forming a continuous, cyclical pulsed reaction without the need for the air pump 610 to operate continuously. This setup, which utilizes the reaction's own energy to maintain the cycle, greatly reduces the system's external energy consumption and achieves highly efficient self-sustaining operation.

[0106] Optionally, the air inlet 524 of the multi-way switching valve 520 is connected to the reactor outlet 420 of the ultraviolet photocatalytic microreactor 400 via the seventh pipeline 550 or directly.

[0107] Please refer to Figure 4 As shown, in some embodiments, the system further includes a positive electrode return line 700 for conveying the positive electrode electrolyte. The negative pressure generating device also includes a Venturi bubble generator 620, which is connected in series to the positive electrode return line 700. The gas return line assembly 500 is supplemented with a sixth line 540, one end of which is connected to the gas inlet of the Venturi bubble generator 620, and the other end is connected to the third gas outlet 523 of the multi-way switching valve 520.

[0108] In this embodiment, the system can start capacity recovery via the Venturi bubble generator 620, as follows:

[0109] Operate the multi-way switching valve 520 to connect its inlet port 524 to the third outlet port 523 of the sixth pipeline 540. When the positive electrolyte flows in the positive return line 700 and passes through the Venturi bubble generator 620 at a sufficiently high flow rate, a negative pressure is generated at its throat. This negative pressure is transmitted through the sixth pipeline 540 and the multi-way switching valve 520 to the ultraviolet photocatalytic microreactor 400 and the upstream gas pipeline, thereby extracting, mixing, and continuously introducing oxidizing and reducing gases into the microreactor, providing the necessary reactants for startup.

[0110] When the mixed gas fills the reaction chamber 480 and reaches a reactivity concentration, the ultraviolet light source 440 ignites the first combustion reaction. The acidic gas generated in this reaction is discharged under instantaneous high pressure, creating an initial negative pressure for subsequent cycles. Afterward, the operable multi-way switching valve 520 switches the flow path, connecting its inlet port 524 to the first outlet port 521 of the fourth pipeline 510, thereby cutting off the flow path of the Venturi bubble generator 620 and putting the system into a self-sustaining cycle state.

[0111] After that, the system will automatically and continuously carry out pulsed reactions by relying on the instantaneous high-pressure exhaust and subsequent negative pressure intake effect generated by each combustion reaction until the gas concentration is lower than the reaction limit.

[0112] Please refer to Figure 5 As shown, in some embodiments, a three-way switching valve 710 is provided on the positive electrode return line 700 to switch the positive electrode return line 700 to flow through or bypass the Venturi bubble generator 620. In a specific example, the positive electrode return line 700 is divided into two independent branches by a three-way switching valve 710 before the return port of the positive electrode storage tank 100, namely the first branch 720 and the second branch 730, which are respectively connected to the first positive electrode return terminal 104 and the second positive electrode return terminal 105. The first positive electrode return terminal 104 and the second positive electrode return terminal 105 can be the same port or different ports. The Venturi bubble generator 620 is installed in series on the first branch 720, while the second branch 730 serves as a bypass path that does not pass through the Venturi bubble generator 620. By operating the three-way switching valve 710, the positive electrolyte can be controlled to flow through either the first branch 720 or the second branch 730.

[0113] In this embodiment, when the positive electrolyte circulation flow rate is large, the system preferentially adopts the Venturi start-up mode. At this time, the three-way switching valve 710 is switched to the first branch 720, allowing the electrolyte to flow through the Venturi bubble generator 620. Simultaneously, the multi-way switching valve 520 is switched so that its inlet port 524 is connected to the third outlet port 523 of the sixth pipeline 540. The electrolyte flowing through the Venturi bubble generator 620 utilizes its kinetic energy to generate sufficient negative pressure. This negative pressure is transmitted through the pipeline, automatically drawing in and mixing oxidizing and reducing gases, and then delivering them to the ultraviolet photocatalytic microreactor 400, completing the initial gas filling and start-up of the system.

[0114] When the positive electrolyte circulation flow rate is low and insufficient to generate an effective negative pressure in the Venturi bubble generator 620, the system switches to the air pump 610 start-up mode. At this time, the three-way switching valve 710 is operated to switch the positive electrolyte return line 700 from the first branch 720 to the second branch 730, allowing the electrolyte to bypass the Venturi bubble generator 620 and reduce system flow resistance. Simultaneously, the multi-way switching valve 520 is operated to connect its inlet port 524 to the second outlet port 522 connected to the fifth line 530. Subsequently, the air pump 610 installed on the fifth line 530 is started. The active suction force generated by the air pump 610 replaces the Venturi effect, taking on the task of driving gas flow and ensuring reliable system startup.

[0115] This system achieves flexible and reliable switching between two drive modes: Venturi negative pressure and air pump 610 negative pressure, through the coordinated operation of the three-way switching valve 710 and the multi-way switching valve 520. This enables the system to adapt to different electrolyte circulation conditions, obtain stable start-up performance, and greatly improve the environmental adaptability and operational reliability of the entire capacity recovery system.

[0116] In some embodiments, one-way valves may be installed on multiple branch lines of the gas return line assembly 500 to further enhance the safety and reliability of system operation.

[0117] Specifically, a second one-way valve 560 may be installed on the fourth pipeline 510. This second one-way valve 560 is configured to allow acidic gas to flow only from the multi-way switching valve 520 to the positive electrode storage tank 100.

[0118] A third one-way valve 580 may be installed on the fifth pipeline 530. This third one-way valve 580 is configured to allow only acid gas to flow from the multi-way switching valve 520 to the positive electrode storage tank 100.

[0119] A fourth one-way valve 570 may be installed on the sixth line 540. This fourth one-way valve 570 is configured to allow gas to flow only to the Venturi bubble generator 620.

[0120] These check valves are designed to strictly prevent reverse flow of gas.

[0121] Please refer to the above as well. Figure 6 and Figure 7 In some embodiments, the ultraviolet photocatalytic microreactor 400 includes a reactor shell 430, an ultraviolet light source 440, and a light-transmitting cover 450.

[0122] The reactor shell 430 constitutes the main body of the ultraviolet photocatalytic microreactor 400, and its interior encloses a sealed reaction chamber 480. The reaction chamber 480 has a first flange 460 and a second flange 470 at its two ends, respectively. The first flange 460 has an inlet end, and the second flange 470 has an outlet end. The two ends of the reaction chamber 480 are connected to the inlet end and the outlet end, respectively, for the inflow of reaction gas and the discharge of generated gas.

[0123] An ultraviolet light source 440 is disposed inside the reaction chamber 480, specifically near the center. Its function is to emit ultraviolet light of a specific wavelength to excite the mixed gas entering the reaction chamber 480 and initiate a combustion reaction.

[0124] A light-transmitting cover 450 is also disposed inside the reaction chamber 480. Its specific structure is a tubular or cylindrical component fitted around the ultraviolet light source 440. The light-transmitting cover 450 physically isolates the ultraviolet light source 440 from the mixed gas flowing through the reaction chamber 480 and the combustion / explosive reaction environment. The light-transmitting cover 450 protects the ultraviolet light source 440, which is sensitive to temperature and chemical environments, from damage caused by the reaction gases and the high temperature, high pressure, or corrosiveness that may result from the violent combustion / explosive reaction. Simultaneously, the material of the light-transmitting cover 450 has high transmittance for ultraviolet light, allowing the energy of the ultraviolet light to efficiently penetrate and act on the surrounding gas-phase reaction zone.

[0125] In this embodiment, placing the ultraviolet light source 440 at the center of the reaction chamber 480 allows for a more uniform distribution of ultraviolet radiation within the annular reaction chamber 480, which is beneficial for initiating a rapid and complete combustion reaction. Furthermore, the physical isolation provided by the light-transmitting cover 450 solves the technical challenge of directly exposing the ultraviolet light source 440 to the harsh reaction environment, significantly improving the lifespan of the ultraviolet light source 440 and the reliability of the entire microreactor. In addition, the compact chamber design helps control the amount of gas produced in a single reaction, keeping the power of the combustion reaction within a safe range.

[0126] In some embodiments, the wall thickness of the reactor shell 430 is set within the range of 5 mm to 10 mm. For example, it can be any value among 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm, or a range between any two values. This thickness range ensures that the shell has sufficient mechanical strength to withstand the periodic pressure shocks generated by the internal combustion and explosion reaction, ensuring the safe operation of the equipment. Simultaneously, the radius of the reactor shell 430 is set between 15 mm and 60 mm. For example, it can be any value among 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 25 mm, 28 mm, 30 mm, 32 mm, 35 mm, 37 mm, 40 mm, 43 mm, 45 mm, 49 mm, 50 mm, 52 mm, 55 mm, 57 mm, and 60 mm, or a range between any two values. This dimensional range directly determines the volume of the reaction chamber 480. The smaller cavity volume is designed to limit the amount of gas involved in a single combustion-explosion reaction, thereby keeping the energy and pressure peaks released by the reaction within safe limits. This is one of the core design concepts of this system for handling high-risk combustion-explosion reactions using microreactors.

[0127] The wall thickness of the light-transmitting cover 450 is set within the range of 5 mm to 10 mm. For example, it can be any value among 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm, or any range between any two values. This thickness selection strikes a balance between mechanical strength and ultraviolet light transmission efficiency. Sufficient wall thickness ensures structural integrity under reaction conditions, especially pressure fluctuations; while controlling the upper limit of its thickness minimizes energy attenuation during ultraviolet light transmission. The radius of the light-transmitting cover 450 is set between 10 mm and 30 mm. For example, it can be any value among 10 mm, 12 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 25 mm, 28 mm, and 30 mm, or any range between any two values. This dimension, together with the radius of the reactor shell 430, defines an annular reaction zone. This annular space allows the mixed gas to flow within the region immediately adjacent to the outer wall of the light-transmitting cover 450, fully absorbing ultraviolet radiation, enabling the reaction to be initiated efficiently and uniformly.

[0128] In some embodiments, the wavelength range of the emitted light waves by the ultraviolet light source 440 is set between 200 nm and 400 nm. This range falls within the ultraviolet light band, and its photon energy is sufficient to effectively break the chemical bonds of oxidizing gas molecules such as chlorine (Cl2) or bromine (Br2), causing them to form highly reactive free radicals, thereby initiating an efficient and rapid gas-phase combustion reaction between them and hydrogen (H2).

[0129] Meanwhile, the power of the ultraviolet light source 440 is set within the range of 5W to 40W. For example, it can be any value or a range between any two values ​​from 5W, 10W, 12W, 15W, 16W, 18W, 19W, 20W, 25W, 28W, 30W, 33W, 38W, to 40W. This ensures that the ultraviolet light source 440 has sufficient energy output to maintain a sufficiently high ultraviolet irradiance within the limited cavity of the ultraviolet photocatalytic microreactor 400, thereby reliably initiating and supporting a continuous combustion reaction. It also controls the system's energy consumption, reducing unnecessary energy loss and equipment costs caused by excessive power usage, while also preventing excessively high local energy density.

[0130] Reference Figure 7As shown, in some embodiments, the reactor shell 430 employs a composite structure. Its outer layer is a metal outer shell layer 431, which provides the necessary structural strength and mechanical support for the entire reactor, enabling it to withstand the periodic pressure generated by the internal combustion and explosion reaction. On the inner surface of the metal outer shell layer 431, i.e., the side in direct contact with the reaction gas, a polymer inner liner layer 432 is provided. The main function of this polymer inner liner layer 432 is to provide excellent corrosion resistance, effectively resisting the erosion of acidic gases (such as hydrogen chloride and hydrogen bromide) generated by the combustion and explosion reaction, thereby protecting the metal shell from corrosion and significantly extending the service life of the microreactor.

[0131] The light-transmitting cover 450 is made of glass, specifically quartz glass with high ultraviolet light transmittance. It can physically isolate the ultraviolet light source 440 from the harsh internal reaction environment, protecting the light source from damage.

[0132] By adopting a composite structure of a metal outer shell layer 431 and a polymer inner liner layer 432, and selecting high-transmittance quartz glass as a light-transmitting cover 450, the ultraviolet photocatalytic microreactor 400 achieves an optimized balance between ensuring structural safety, resisting harsh reaction environments, and maintaining efficient photochemical conversion, thus ensuring the reliability and stability of the core components during long-term operation.

[0133] Optionally, the metal outer shell layer 431 can be made of stainless steel, and the polymer inner lining layer 432 can be made of polytetrafluoroethylene.

[0134] In some embodiments, the flow battery capacity recovery system includes multiple ultraviolet photocatalytic microreactors 400. These microreactors are integrated in parallel within the system.

[0135] Specifically, the inlet of each UV photocatalytic microreactor 400 is connected to the common inlet pipeline assembly 300. The mixed gas generated and mixed by the positive electrode storage tank 100 and the negative electrode storage tank 200 is simultaneously distributed and transported to each of the parallel UV photocatalytic microreactors 400. The outlet of each UV photocatalytic microreactor 400 is also connected to the common gas return pipeline assembly 500. The acidic gas generated by the combustion reaction in all UV photocatalytic microreactors 400 flows into the same return pipeline and is ultimately transported back to the positive electrode storage tank 100 for absorption.

[0136] This parallel configuration linearly increases the total gas throughput per unit time by increasing the number of reaction units, enabling the system to adapt to flow batteries of different capacities and scales, thus enhancing the versatility and scalability of the solution. Secondly, multiple reactors can operate simultaneously, and the number activated can be flexibly adjusted according to the actual gas production, achieving modular adjustment of processing capacity and energy efficiency optimization. Finally, this design also improves system redundancy; even if a single microreactor needs to be shut down for maintenance or failure, the remaining reactors can continue to operate, ensuring the continuity of the capacity recovery process and the overall reliability of the system.

[0137] Accordingly, this application also provides a flow battery capacity recovery method. This method achieves capacity recovery based on a physical-photochemical process, directly utilizing the gaseous byproducts generated inside the battery system, and effectively restoring the balance of active substances in the electrolyte through in-situ conversion and reuse.

[0138] See Figure 8 As shown, the method mainly includes the following steps:

[0139] First, gas collection and mixing are performed. The oxidizing gas generated by the positive electrode electrolyte in the positive electrode storage tank 100 is mixed with the reducing gas generated by the negative electrode electrolyte in the negative electrode storage tank 200 to form a homogeneous mixed gas. The oxidizing gas is typically chlorine or bromine, and the reducing gas is typically hydrogen.

[0140] Next, a photochemical combustion reaction is carried out. The above-mentioned mixed gas is passed into an ultraviolet photocatalytic microreactor 400. The mixed gas is irradiated with ultraviolet light of a specific wavelength generated by an ultraviolet light source 440 within the ultraviolet photocatalytic microreactor 400, initiating a rapid combustion reaction. This reaction converts the mixed gas into an acidic gas, such as hydrogen chloride or hydrogen bromide.

[0141] Next, the acidic products are recovered. The acidic gas generated by the combustion reaction is passed into the positive electrode electrolyte to ensure its full absorption. After being absorbed by the positive electrode electrolyte, the acidic gas can provide hydrogen ions and participate in the system balance, thereby correcting the ion imbalance in the positive and negative electrode electrolytes caused by side reactions such as hydrogen evolution at the negative electrode, and restoring the battery capacity.

[0142] The entire method does not require the introduction of any external chemical restorers or heterogeneous catalysts, thus avoiding electrolyte contamination and achieving clean and efficient flow battery capacity recovery.

[0143] The generation of reducing gas originates from inherent side reactions during the operation of the flow battery. During battery charging or high-potential operation, the negative electrode electrolyte in the negative electrode storage tank 200 undergoes a hydrogen evolution reaction (2H₂O). + +2e -=H2. Specifically, hydrogen ions in the electrolyte gain electrons at the negative electrode and are reduced to generate hydrogen gas. The continued occurrence of this side reaction leads to a change in the total amount of active material at the negative electrode, which is one of the direct causes of battery capacity decay.

[0144] Oxidizing gases are actively generated through chemical reactions within the positive electrode electrolyte when the battery is in a high state of charge (high SOC). The positive electrode electrolyte contains a specific concentration of reducing ions and active ions of different valence states. As the battery's state of charge increases, the higher-valence active ions react with the reducing ions in a redox reaction. In this reaction, the reducing ions are oxidized to generate the corresponding oxidizing gas; simultaneously, the higher-valence active ions are reduced to lower valence states. For example, in a vanadium electrolyte containing chloride ions, pentavalent vanadium ions react with chloride ions to generate chlorine gas, while the pentavalent vanadium is reduced to tetravalent vanadium. The reaction is as follows:

[0145] 2VO 2 + +2Cl - +4H + 2VO 2+ +Cl 2 +2H 2 O

[0146] In the positive electrode storage tank 100, the dynamic balance of chlorine gas evolution will maintain the chlorine content in the atmosphere to a certain extent.

[0147] Oxidizing and reducing gases mix to form a mixed gas. When this mixed gas enters the reaction chamber 480 of the ultraviolet photocatalytic microreactor 400, the combustion reaction is instantly initiated under the irradiation of the ultraviolet light source 440. The reaction is as follows;

[0148] H 2 +Cl 2 =2HCl (illumination)

[0149] The process is roughly as follows:

[0150] Ultraviolet light of a specific wavelength penetrates the light-transmitting shield 450, and its photon energy is preferentially absorbed by the oxidizing gas molecules in the mixed gas. This causes the chemical bonds of the oxidizing gas molecules to break, dissociating and generating highly reactive atoms or free radicals. These newly generated reactive species react violently with the reducing gas molecules in the mixed gas. This reaction propagates rapidly in the gas phase in the form of a chain reaction, completing within milliseconds and releasing a large amount of heat. The exothermic reaction causes the temperature and pressure of the generated gaseous products to rise sharply within the sealed cavity, forming an instantaneous high-pressure zone. This high pressure generates a strong driving force. Driven by the high pressure, the acidic gas generated in the reaction is propelled at high speed to and discharged from the reactor outlet 420, entering the gas return pipeline. The acidic gas is then transported to the positive electrode storage tank 100 for absorption. After the high-temperature gas is discharged, the pressure in the reaction chamber 480 drops rapidly, forming a brief negative pressure zone. This negative pressure automatically draws in a new round of mixed gas from the upstream inlet pipeline, preparing for the next combustion reaction.

[0151] Therefore, under continuous ultraviolet light, the above process can form a periodic pulsed cycle until the gas concentration is insufficient to maintain the reaction.

[0152] This method utilizes the by-reaction products that cannot be completely avoided during the operation of the battery system, as well as the oxidizing gas that can be actively generated by controlling the battery state, without introducing any additional chemical substances from the outside.

[0153] In some embodiments, the method drives the flow of all gases in the system by actively generating a negative pressure. This negative pressure acts on the gas circuit, providing a unified power source for the extraction of oxidizing gas from the positive electrode storage tank 100, the extraction of reducing gas from the negative electrode storage tank 200, and the return of acidic gas from the ultraviolet photocatalytic microreactor 400 to the positive electrode storage tank 100.

[0154] This negative pressure drive ensures stable and controllable gas flow throughout the entire capacity recovery process, overcoming pipeline resistance and guaranteeing timely delivery of reactants and products, enabling the recovery process to proceed continuously and automatically.

[0155] In some embodiments, the method generates the required negative pressure by activating a gas pump 610. The gas pump 610 is typically installed on a gas return line connecting the outlet of the ultraviolet photocatalytic microreactor 400 to the inlet of the positive electrode reservoir 100.

[0156] When the gas pump 610 starts working, it generates a suction force on its own inlet side. This suction force is transmitted through the pipeline, acting directly on the reaction chamber 480 of the ultraviolet photocatalytic microreactor 400, and further transmitted to the upstream inlet pipeline, thus forming the driving force for the flow of oxidizing and reducing gases. At the same time, a pushing force is generated on the outlet side of the gas pump 610, effectively delivering the acidic gas generated in the reaction to the positive electrode storage tank 100.

[0157] By controlling the start and stop of the air pump 610, gas circulation can be established or terminated as needed, providing the system with a stable, reliable, and easily controllable source of gas driving force.

[0158] In some embodiments, the method generates the required negative pressure by allowing the positive electrolyte to flow through a Venturi bubble generator 620 in the positive return line 700. When the positive electrolyte flows through the throat of the generator at a certain flow rate, its kinetic energy increases, leading to a decrease in static pressure, thereby creating a negative pressure zone in the throat, according to the principles of fluid dynamics.

[0159] This negative pressure is transmitted to the ultraviolet photocatalytic microreactor 400 cavity and upstream inlet pipe through a pipeline (i.e., sixth pipeline 540) connecting the gas inlet of the Venturi bubble generator 620 and the gas circuit. This negative pressure can simultaneously draw out the oxidizing gas and the reducing gas from their respective storage tanks and promote their mixing and flow into the microreactor.

[0160] This method utilizes the kinetic energy of the circulating electrolyte within the system, converting it into a negative pressure source that drives gas flow, thus achieving a cascaded utilization of energy and helping to reduce the additional energy consumption of the entire capacity recovery process.

[0161] In some embodiments, the method includes active control of the positive electrolyte flow path. When the circulating flow rate of the positive electrolyte is monitored or determined to be lower than a preset value, that is, its flow rate is insufficient to drive the Venturi bubble generator 620 to generate an effective negative pressure.

[0162] At this point, a switching operation is performed. The flow path of the positive electrolyte is switched from the path flowing through the Venturi bubble generator 620 (i.e., the first branch 720) to a bypass path that bypasses the generator (i.e., the second branch 730). This reduces the total flow resistance of the positive electrolyte return line 700, ensuring smooth electrolyte circulation.

[0163] Simultaneously, the air pump 610 installed in the gas return line is started. The active suction force generated by the operation of the air pump 610 replaces the failed Venturi negative pressure and takes on the task of driving the gas flow of the entire system, thereby ensuring that the flow battery capacity recovery process can be reliably started and continue.

[0164] This method achieves adaptive matching between the drive mode and system operating conditions by linking the flow path switching with the start and stop of the air pump 610, ensuring that the system can obtain stable gas driving force under different electrolyte circulation conditions.

[0165] In some embodiments, the method further includes using the energy generated by the combustion-explosion reaction itself to drive subsequent reactions. Specifically, after a combustion-explosion reaction is completed, the high-temperature gaseous products are instantly discharged from the reaction chamber 480, causing a sudden drop in pressure within the chamber and creating a significant instantaneous negative pressure. This negative pressure generates a strong suction effect through the intake pipe, automatically drawing new mixed gas from upstream into the reaction chamber 480, thereby replenishing the reactants.

[0166] Subsequently, under continuous ultraviolet light irradiation, the newly added mixed gas is re-ignited, triggering another combustion-explosion reaction. This process of reaction, exhaust, intake, and re-reaction forms a complete self-driven cycle. This cycle repeats continuously and automatically without external power to maintain gas flow until the concentration of the reducing gas precipitated in the negative electrode storage tank 200 gradually decreases below the concentration limit required for the combustion-explosion reaction, at which point the reaction can no longer be initiated. At this point, the cycle automatically stops, and the capacity recovery procedure is completed.

[0167] This fully utilizes the energy of the reaction itself, minimizes the system's operating energy consumption, and gives the entire recovery process a high degree of autonomy.

[0168] In some embodiments, after an acidic gas is introduced into the positive electrolyte and absorbed, the state of charge of the positive electrolyte changes. Through this recovery process, the state of charge of the positive electrolyte can be maintained or adjusted to the range of 50% to 100%.

[0169] In one specific example, before the recovery procedure is initiated, the state of charge of the positive electrolyte is adjusted to the range of 60% to 100%. After the recovery procedure is completed, the state of charge of the positive electrolyte is in the range of 50% to 100%.

[0170] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0171] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0172] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0173] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A flow battery capacity recovery system, characterized by, The system comprises: a positive electrode liquid storage tank containing positive electrode electrolyte capable of generating oxidizing gas; a negative electrode liquid storage tank containing negative electrode electrolyte capable of generating reducing gas; an air inlet pipeline assembly and an ultraviolet light catalytic micro-reactor, an air inlet end of the ultraviolet light catalytic micro-reactor being connected to the positive electrode liquid storage tank and the negative electrode liquid storage tank through the air inlet pipeline assembly; the ultraviolet light catalytic micro-reactor is used to receive mixed gas of the oxidizing gas and the reducing gas, and initiate combustion and explosion reaction of the mixed gas under ultraviolet light irradiation to generate acidic gas; wherein the ultraviolet light catalytic micro-reactor comprises a reactor shell, an ultraviolet light source and a light-transmitting cover, the reactor shell surrounds a reaction cavity, the reaction cavity is communicated with an air inlet end and an air outlet end of the ultraviolet light catalytic micro-reactor; the ultraviolet light source is arranged in the reaction cavity; the light-transmitting cover is arranged in the reaction cavity and is sleeved on the outer periphery of the ultraviolet light source; a gas backflow pipeline assembly connecting the air outlet end of the ultraviolet light catalytic micro-reactor and the positive electrode liquid storage tank, and used to transport the acidic gas to the positive electrode liquid storage tank so that the acidic gas is absorbed by the positive electrode electrolyte.

2. The flow battery capacity restoration system of claim 1, wherein, The air inlet pipeline assembly comprises: a first pipeline connecting an air outlet end of the positive electrode liquid storage tank; a second pipeline connecting an air outlet end of the negative electrode liquid storage tank; a three-way mixer, one air inlet end of which is connected to the first pipeline, and the other air inlet end of which is connected to the second pipeline, an air outlet end of the three-way mixer being used to output the mixed gas; a third pipeline connecting the air outlet end of the three-way mixer and the air inlet end of the ultraviolet light catalytic micro-reactor.

3. The flow battery capacity restoration system of claim 2, wherein, The air inlet pipeline assembly further comprises a first one-way valve, which is arranged on the third pipeline and is configured to allow the mixed gas to flow from the three-way mixer to the ultraviolet light catalytic micro-reactor.

4. The flow battery capacity restoration system of claim 2, wherein, The diameter of the first pipeline is 1 to 3 times the diameter of the second pipeline.

5. The flow battery capacity restoration system of claim 1, wherein, The gas backflow pipeline assembly comprises a fourth pipeline, one end of the fourth pipeline being connected to the air outlet end of the ultraviolet light catalytic micro-reactor, and the other end of the fourth pipeline being connected to the air inlet end of the positive electrode liquid storage tank.

6. The flow battery capacity restoration system of claim 5, wherein, The flow battery capacity recovery system further comprises a negative pressure generating device, which is used to drive the flow of the oxidizing gas, the reducing gas and the acidic gas.

7. The flow battery capacity restoration system of claim 6, wherein, The negative pressure generating device comprises a gas pump, which is arranged on the fourth pipeline.

8. The flow battery capacity restoration system of claim 6, wherein, The gas backflow pipeline assembly further comprises a multi-way switch valve and a fifth pipeline; one end of the fourth pipeline is connected to a first air outlet interface of the multi-way switch valve to be connected to the air outlet end of the ultraviolet light catalytic micro-reactor through the multi-way switch valve; one end of the fifth pipeline is connected to a second air outlet interface of the multi-way switch valve, and the other end of the fifth pipeline is connected to the air inlet end of the positive electrode liquid storage tank. The negative pressure generating device comprises a gas pump, which is arranged on the fifth pipeline.

9. The flow battery capacity restoration system of claim 8, wherein, The flow battery capacity recovery system further comprises a positive electrode liquid return pipeline for transporting positive electrode electrolyte, and the gas backflow pipeline assembly comprises a sixth pipeline. The negative pressure generating device comprises a Venturi bubble generator arranged on the positive liquid return pipeline and connected to the third gas outlet interface of the multi-way switching valve through the sixth pipeline.

10. The flow battery capacity restoration system of claim 9, wherein, A three-way switching valve is arranged on the positive liquid return pipeline to switch the positive liquid return pipeline to flow through the Venturi bubble generator or bypass the Venturi bubble generator.

11. The flow battery capacity restoration system of claim 9, wherein, A second one-way valve is arranged on the fourth pipeline, and the second one-way valve is configured to allow the flow of the acidic gas to the positive liquid tank; and / or, A third one-way valve is arranged on the fifth pipeline, and the third one-way valve is configured to allow the flow of the acidic gas to the positive liquid tank; and / or, A fourth one-way valve is arranged on the sixth pipeline, and the fourth one-way valve is configured to allow the flow of the acidic gas to the Venturi bubble generator.

12. The flow battery capacity restoration system of claim 1, wherein, The wall thickness of the reactor shell is 5mm to 10mm, and the radius is 15mm to 60mm; and / or, The wall thickness of the light-transmitting cover is 5mm to 10mm, and the radius is 10mm to 30mm.

13. The flow battery capacity restoration system of claim 1, wherein, The wavelength of the ultraviolet light source is 200nm to 400nm, and the power is 5W to 40W.

14. The flow battery capacity restoration system of claim 1, wherein, The reactor shell comprises a metal shell layer and a polymer lining layer arranged on the inner surface of the metal shell layer; and / or, The material of the light-transmitting cover is glass.

15. The flow battery capacity restoration system of claim 1, wherein, The liquid flow battery capacity recovery system comprises a plurality of ultraviolet light catalytic micro-reactors arranged in parallel, and the gas inlet end of each ultraviolet light catalytic micro-reactor is connected to the gas inlet pipeline assembly, and the gas outlet end of each ultraviolet light catalytic micro-reactor is connected to the gas return pipeline assembly.

16. A method of flow battery capacity recovery, comprising: The liquid flow battery capacity recovery method is applied to the liquid flow battery capacity recovery system as claimed in any one of claims 1 to 15, and the method comprises: Mixing the oxidation gas generated by the positive electrolyte in the positive liquid tank and the reduction gas generated by the negative electrolyte in the negative liquid tank to form a mixed gas; Passing the mixed gas into the ultraviolet light catalytic micro-reactor and initiating a combustion explosion reaction under ultraviolet light irradiation to generate acidic gas; Passing the acidic gas into the positive electrolyte for absorption.

17. The flow battery capacity restoration method of claim 16, wherein, Driving the flow of the oxidation gas, the reduction gas and the acidic gas by negative pressure.

18. The flow battery capacity restoration method of claim 17, wherein, Generating the negative pressure by a gas pump.

19. The flow battery capacity restoration method of claim 17, wherein, Generating the negative pressure by making the positive electrolyte flow through the Venturi bubble generator.

20. The flow battery capacity restoration method of claim 19, wherein, When the flow rate of the positive electrolyte is lower than a preset value, switching the flow path of the positive electrolyte to bypass the Venturi bubble generator; and starting the gas pump to generate the negative pressure.

21. The flow battery capacity restoration method of claim 16, wherein, The liquid flow battery capacity recovery method further comprises: Using the instantaneous negative pressure generated after the completion of the combustion explosion reaction to automatically suck new mixed gas into the ultraviolet light catalytic micro-reactor to repeatedly perform the combustion explosion reaction until the concentration of the reduction gas is lower than the combustion explosion reaction concentration limit.

22. The flow battery capacity restoration method of claim 16, wherein, The oxidation gas is chlorine or bromine, and the reduction gas is hydrogen.

23. The flow battery capacity restoration method of claim 16, wherein, The wavelength of the ultraviolet light in the ultraviolet light catalytic micro-reactor is 200nm to 400nm.

24. The flow battery capacity restoration method of claim 23, wherein, The power of the ultraviolet light in the ultraviolet light catalytic micro-reactor is 5W to 40W.

25. The flow battery capacity restoration method of claim 16, wherein, The step of absorbing the acid gas into the catholyte after the step of absorbing the acid gas into the catholyte has a state of charge of 50% to 100%.

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